This invention relates to locking and unlocking of a mechanical lock device by use of momentary electrical power.
Locks operated by use of electricity are widely known and used today. Virtually every mechanical lock manufacturer offers a model which is electrically operated. The operation of these locks is divided into two categories: 1) fail-safe, and 2) fail-secure.
Both of these systems (fail-safe and fail-secure) commonly utilize a push or pull type solenoid to achieve the locking and unlocking, and require to be powered or unpowered for a set amount of time or until the door is opened (if being monitored).
In fail-safe locks, the lock is locked by continuous power and is opened by interruption of the power. These systems are used in emergency exit doors where in the case of power failure or other types of emergencies, the lock unit will automatically be unlocked. Since the operation of this unit requires continuous power to stay locked, they are powered by the building's electricity (wired) and are not suitable for battery operation.
In fail-secure locks, which are more commonly used in access control systems, the lock is normally locked until powered. Theoretically, this type of lock unit can be operated by either the building's electricity or by battery power since it requires only momentary power for operation. However, battery operation becomes unsuitable for this operation as well, due to the problem described below.
The common problem associated with the locking and unlocking of the lock device is that, in anticipation of entering, the person seeking access tries to push or turn the lock's lever or knob mechanism during or prior to the unit being powered, thus causing the locking pin of the solenoid to jam. Only when the lever or knob mechanism is released by the person seeking access, is the solenoid able to pull or push the locking pin for its operation. Due to this, an extensive period of powering of the solenoid is required in order to complete the operation. This becomes unsuitable for lock units that rely on a battery for power, because it requires frequent replacement of the batteries.
Magnetic latching solenoids that operate using momentary power have existed for some time. These solenoids require a very short pulse of power to change position, and they stay in their new position until powered again in the reverse polarity.
However, magnetic latching solenoids are not suitable. This is because if the person seeking access is placing pressure on the lock's knob or lever during the period of powering of the solenoid, the solenoid will not be able to perform its function. Or if the person seeking access continues to hold the knob or lever of the lock mechanism in a turned position after the unlocking of the lock, during which the solenoid is being powered for locking the lock mechanism, then the locking pin of the solenoid will be unable to enter into the locking hub. Therefore, again the solenoid will not be able to perform its function, making this type of solenoid unsuitable.
In U.S. Pat. No. 4,656,850 Tabata, issued Apr. 14, 1987, a magnetic latching solenoid is utilized. Tabata teaches the functionings of a magnetic latching solenoid and its application in his electric lock. Tabata's use of a magnetic latching solenoid is theoretical. Tabata's electric lock does not address the real-life application problems referenced above with the use of this type of solenoid. Additionally, given the quantity of components required in Tabata's lock and the limited amount of free space available in any given existing lock, the mechanisms contained in Tabata's lock are not suitable for converting existing mechanical locks to operate electrically using momentary power.
The current invention overcomes the problems addressed above with a conversion apparatus (or as OEM equipment) operated by momentary power.
In the current invention, with the use of the apparatus, the locking and unlocking of the lock is provided by use of momentary power, in a way such that successful completion of the operation is achieved regardless of whether or not there is pressure being placed on the lock's knob or lever by the person seeking access. Additionally, the size and shape of the conversion apparatus makes the conversion to operation by momentary power possible for virtually any lock.